1. Field of the Invention
The invention relates to a light guide device, and more particularly to an illumination module using the light guide device suitable for installation in a scanning apparatus, a multifunction peripheral, a facsimile machine or the like.
2. Description of the Related Art
The light source utilized in a conventional scanning device is a cold cathode fluorescent lamp (CCFL). Before a scanning action begins, it is necessary to warm up the CCFL until the illumination of the CCFL attains a steady state. The life span of the CCFL is about ten thousand hours, which places limitations on usage time. The CCFL also has relatively lower illumination efficiency and larger heat dissipation during illumination. Additionally, CCFL power consumption is relatively high. Thus, there are many drawbacks for using the cold cathode fluorescent lamp as the light source.
As shown in FIG. 1, a conventional scanning device 1 incorporating the light-emitting diode (LED) includes a body 11, a transparent plate 12, a light module 13, a reflecting module 14, and an image capturing element 15. The body 11 further has a chamber 111 for reflecting, and the reflecting module 14 is installed therein. The transparent plate 12 is above the body 11, and the light module 13 is located on the body 11 and disposed between the transparent plate 12 and the body 11. The light module 13 has a plurality of LEDs 131 arranged in a linear array and a cylindrical lens 132 sheltering the LEDs 131. The cylindrical lens 132 has a receiving surface 133 adjacent to the LEDs 131 and an emitting surface 134, wherein the emitting surface 134 has a radius curvature. The light emitted from the LEDs 131 of the light module 13 will enter the cylindrical lens 132 via receiving surface 133, and then be transmitted onto an article 16 located on the transparent plate 12 after passing through the emitting surface 134 and the transparent plate 12 in sequence. Moreover, the light is reflected into the chamber 111 by the article 16, and then the light is received and transformed into electronic signals by the image capturing element 15 after reflecting the light by the reflecting module 14.
However, the conventional scanning device 1 has a disadvantage where the intensity of the light module 13 is not uniform. In conventional scanning device 1, each LEDs 131, as a light point, is arranged apart from each other. Thus, uniform illumination for incident light can not be achieved, even if illumination is increased by the light source.